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// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.skyframe;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.skyframe.GraphTester.ValueComputer;
import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.CountDownLatch;
import javax.annotation.Nullable;
/**
* {@link ValueComputer} that can be chained together with others of its type to synchronize the
* order in which builders finish.
*/
public final class ChainedFunction implements SkyFunction {
@Nullable private final SkyValue value;
private final Runnable notifyStart;
@Nullable private final CountDownLatch waitToFinish;
private final Runnable notifyFinish;
private final boolean waitForException;
private final Iterable<SkyKey> deps;
/** Do not use! Use {@link Builder} instead. */
ChainedFunction(
@Nullable CountDownLatch notifyStart,
@Nullable CountDownLatch waitToFinish,
@Nullable CountDownLatch notifyFinish,
boolean waitForException,
@Nullable SkyValue value,
Iterable<SkyKey> deps) {
this(
makeRunnable(notifyStart),
waitToFinish,
makeRunnable(notifyFinish),
waitForException,
value,
deps);
}
private ChainedFunction(
Runnable notifyStart,
@Nullable CountDownLatch waitToFinish,
Runnable notifyFinish,
boolean waitForException,
@Nullable SkyValue value,
Iterable<SkyKey> deps) {
this.notifyStart = notifyStart;
this.waitToFinish = waitToFinish;
this.notifyFinish = notifyFinish;
this.waitForException = waitForException;
Preconditions.checkState(this.waitToFinish != null || !this.waitForException, value);
this.value = value;
this.deps = deps;
}
@Override
public SkyValue compute(SkyKey key, SkyFunction.Environment env) throws GenericFunctionException,
InterruptedException {
try {
notifyStart.run();
if (waitToFinish != null) {
TrackingAwaiter.INSTANCE.awaitLatchAndTrackExceptions(
waitToFinish, key + " timed out waiting to finish");
if (waitForException) {
SkyFunctionEnvironment skyEnv = (SkyFunctionEnvironment) env;
TrackingAwaiter.INSTANCE.awaitLatchAndTrackExceptions(
skyEnv.getExceptionLatchForTesting(), key + " timed out waiting for exception");
}
}
for (SkyKey dep : deps) {
env.getValue(dep);
}
if (value == null) {
throw new GenericFunctionException(new SomeErrorException("oops"),
Transience.PERSISTENT);
}
if (env.valuesMissing()) {
return null;
}
return value;
} finally {
notifyFinish.run();
}
}
private static Runnable makeRunnable(@Nullable CountDownLatch latch) {
return latch != null ? latch::countDown : () -> {};
}
/** Builder for {@link ChainedFunction} objects. */
public static class Builder {
@Nullable private SkyValue value;
Runnable notifyStart = makeRunnable(null);
@Nullable private CountDownLatch waitToFinish;
private Runnable notifyFinish = makeRunnable(null);
private boolean waitForException;
private Iterable<SkyKey> deps = ImmutableList.of();
@CanIgnoreReturnValue
public Builder setValue(SkyValue value) {
this.value = value;
return this;
}
@CanIgnoreReturnValue
public Builder setNotifyStart(Runnable notifyStart) {
this.notifyStart = notifyStart;
return this;
}
@CanIgnoreReturnValue
public Builder setWaitToFinish(CountDownLatch waitToFinish) {
this.waitToFinish = waitToFinish;
return this;
}
@CanIgnoreReturnValue
public Builder setNotifyFinish(Runnable notifyFinish) {
this.notifyFinish = notifyFinish;
return this;
}
@CanIgnoreReturnValue
public Builder setWaitForException(boolean waitForException) {
this.waitForException = waitForException;
return this;
}
@CanIgnoreReturnValue
public Builder setDeps(Iterable<SkyKey> deps) {
this.deps = Preconditions.checkNotNull(deps);
return this;
}
public SkyFunction build() {
return new ChainedFunction(
notifyStart, waitToFinish, notifyFinish, waitForException, value, deps);
}
}
}